Flat refrigerating unit with counter current cooling

ABSTRACT

The aim of the invention is to improve the performance of heat exchangers such that lost heat is discharged from a cabinet or device, whereby the rise of the inner temperature for each discharged watt of power loss is only slight. The invention also relates to a flat refrigerating set. The temperature of the heated air (SL,) can be reduced in the counterflow (L 4 ;L 3 ;k 1 ;k 2  . . . ) by means of counterflowing cooling air (KL) without the cooling air physically entering into contact with the heated air flow (L 1 ,L 3 ,L 5 ) that is to be cooled. The air flow to be cooled (SL) can be supplied to several parallel first chambers (k 1 ,k 3 ,k 7 ) via an inlet area ( 13 ). The parallel first and parallel second chambers alternate in the direction of the height or density (h) of the refrigerating unit. The alternating chambers (k 1 ,k 2 ,k 3 ,k 4 , . . . ) also extend into a section of the flat cooling unit (l 13 ), which is located between the inlet area ( 13 ) and a closer end ( 40,41 ) of the refrigerating unit.

The invention relates to a flat refrigerating unit for use as a heatexchanger for cooling air from (for example) a device cabinet, a servercabinet or a circuit cabinet, in which heat-generating equipment isinstalled, the heat of which is to be removed from the essentiallyclosed housing array, in order to prevent the internal temperature ofthese cabinet arrays from exceeding a predetermined maximum value.

Heat exchangers as such, in the sense of a countercurrent principle inwhich refrigerating air flows in one direction and, in separate flowchambers, the air to be cooled flows in the opposite direction, arealready known in the art. See, for example DE-A 30 44 135 (Siemens),which describes a heat exchanger with flow channels, the cross-sectionsof which are oriented essentially perpendicular to the flat side of theheat exchanger and extend longitudinally; also see, [in DE-A 30 44 135,]FIG. 2 and, regarding the countercurrent principle, column 6, lines 10to 20. To charge the refrigerating chambers oriented in this manner withthe air to be cooled, radial fans or tangential fans are used, which areinstalled in triangular storage chambers at the ends of the heatexchanger, so as to axially draw in the air and radially force it intothe storage chambers (at the inlet for the air to be cooled). The samealso applies at the inlet for the refrigerating air located at theopposite end. The purpose of the described solution of the prior art isto distribute the flowing air virtually uniformly across all flowchannels, while maximally utilizing the housing volume for the heatexchanger.

An exchanger array that does not employ the countercurrent principle isdescribed in DE-A 198 04 904 (Rittal), for example, where specificlocations in the interior space that are subject to elevated heatdischarge can be separately cooled with tubes, wherein these coolingtubes can be easily adjusted to conform to various configurations of theinterior space (see, [in DE-A 198 04 904,] the sole figure, as well ascolumn 1, lines 54 to 58). A double-walled element on the cabinet (back)side allows heat exchange, although a countercurrent principle is notemployed.

The aim of the invention is to further increase the performance capacityof a heat exchanger, wherein the lost heat is to be removed from thecabinet or, if applicable, a device of the same size, so that a slightincrease in the internal temperature per discharged watt of power lossarises (°K per watt or W/°K).

The aim is achieved with a flat refrigerating unit using thecountercurrent principle, according to at least one of the independentclaims 1 to 6 or 20. Preferably, the inventions described therein canalso be combined (claim 7), specifically at least two of the solutionsdescribed therein.

The air in the internal circuit and in the external circuit is conductedprecisely in a countercurrent, achieving maximum effectiveness. Insteadof radial fans, axial fans are used; their performance capacity issignificantly higher (claim 8) and, furthermore, they present fewerdiversions for the movement of the (flowing) air. The axially drawn-inair is also discharged axially and forced into the countercurrent heatexchanger in the inlet area, while the same type of axial fan—spaced ata distance from the inlet area—can also be arranged at the outlet area.Said axial fan then extracts refrigerated air from the heat exchangerand returns it to the circuit cabinet, server cabinet or device cabinet,or into a single large device (claim 16, 17). The increase in heatexchange is favorably influenced by a difference in the performancecapacity, the set rotation speed or the size of the two fans producingthe airflow to be cooled. The fan at the inlet area should be operatedor capable of being operated at a higher rotation speed than that in theoutlet area. With regard to the refrigerating air, which is alsoprovided by two axial fans operating in accordance with thecountercurrent principle, it is advantageous if these two fans, one atthe inlet area of the refrigerating air and one at the outlet area ofthe refrigerating air (the exhaust air), possess essentially the sameperformance capacity, rotation speed or performance setting. Despite thefact that the maximum possible volume of refrigerating air is provided,the increased introduction of the air to be cooled results in anincrease in the dwell time of the air to be cooled and—based on thecurrent level of knowledge—also increases turbulence within the flowchambers, which results in improved heat exchange with thecounterflowing refrigerating air.

The flow path of the refrigerating air is virtually straight-lined(claim 1). Between the outlet of the first fan and the second fan, thepath of the refrigerating air progresses practically in a straight linethrough the chambers, interrupted only by the inlet area and the outletarea of the air to be cooled, which does not enter into contact with therefrigerating air, but instead is conducted through separate chambersusing the countercurrent principle.

Instead of one fan, several fans can also be connected in parallel,depending on the formation, form and size of the flat refrigeratingunit.

The U-shaped formation of the flow path of the air to be cooled hasproven advantageous in that this air is subject to as few diversions aspossible during its flow path (claim 2), wherein the axial fanscontribute to this effect. Beginning at an inlet area, especially in thecylindrical design, air is forced into a first storage chamber, which isoverpressured as a result of the first fan. From this storage chamber,the air is distributed across a plurality of parallel flat chambers,which extend flatly in parallel to the flat side of the heat exchanger.At the outlet area, which is oriented at a significant distance from theinlet area, oriented primarily perpendicular to the flat side of theheat exchanger, the cooled air from the individual, parallel and spacedflat chambers re-accumulates in an essentially cylindrical collectionspace, from which it is returned, as cooled air, into the area in whichthe heat arises. An additional axial fan (referred to in the claims asfourth fan), which extracts the air from the collection space, butpreferably with a lower output that that of the first fan, whichintroduces the air into the first storage space, can be oriented at thispoint.

With this type of design, it is possible to fully utilize the availableinstalled length and therefore the surface area of the sheet metalhousing used for heat exchange, also eliminating the need to clear orcreate space for a fan in the sheet metal housing itself. In addition,the location and installed height of the flat flow channels results in aturbulent flow, which preferably provides heightened exchangerperformance in panels with uneven surfaces (claim 11).

The flow chambers, referred to as flat chambers, for the air to becooled as well as for the refrigerating air, preferably have only aslight height along their width and length (claim 5). Width and height,in this context, refers to the fact that these two dimensions describe aplane in parallel to the flat side of the heat exchanger, whereas theheight is defined in the direction of the thickness, that is,perpendicular to the flat extension of the flat refrigerating unit.

In addition, the exchanger performance is increased by the fact thatcountercurrent exchange does not only occur after the inlet and up tothe outlet for the air to be cooled, but also downstream from the outlet(claim 4) and upstream from the inlet (claim 3).

The flat flow chambers for refrigerating air and air to be cooled, whichare alternately arranged in the countercurrent principle, also extendbetween the outflow end of the heat exchanger and the inlet area, aswell as between the inflow end for the refrigerating air and the outletarea for the air to be cooled, which at this point is already referredas “cooled air.”

With regard to terminology, it should be noted that the “air to becooled” refers to the air that is turned over as consumed air within thecabinet system and is thereby cooled. It has the lowest possibletemperature upon exiting and is described here as cooled air, butalso—in describing the cycle—as air to be cooled during the course ofits overall path. The useful air, with which the heat exchanger iscooled, referred to as refrigerating air, and is called exhaust air inthe outlet area, that is, where it has its maximum temperature.Nevertheless, the refrigerating air is still referred to as such duringits entire flow path in the exchanger, so as to maintain the mostuniform terminology possible for the invention being described.

It should also be noted that when describing a flat refrigerating unit,the function and mode of the unit's operation is often described byusing the airflows and the flowing air, although this should not beunderstood to be so restrictive as to refer only to current operation.Instead, current operation is covered by a process claim (claim 20),which explains that the inlet area and the outlet area for the air to becooled are not the ends of the respective heat exchanger, but ratherthat cooling areas in the countercurrent principle are also locatedbetween these areas and the respective front end (beginning). This isdescribed in such a way that refrigerating air cooling past the inletarea is still capable of flowing [and], alternatively or cumulatively,fresh air still cooling behind the outlet area for the cooled air canalso be used in the countercurrent heat exchange principle.

When the refrigerating air is still flowing past the inlet area for theair to be cooled and the cooling air is already flowing in front of theoutlet area (claim 21), this is provided in the respective inlet andoutlet areas (for the air to be cooled) in such a way that it occursalong a width which is not less than the width, especially the diameter,of the inflow area or the outflow area itself (claim 21).

The distance between the metallic sheets separating the chambers (claim23, claim 6) can be deduced from the height of the flowing air layers(claim 23). The latter chambers are sealed with dividers in the form offins, creating separate, alternating chamber systems for the cooling airand for the air to be cooled (claims 6, 19, 18, 9, 10).

An additional increase in cooling performance or heat loss performancein the heat exchanger can be achieved with blocking elements (claim 12),which block a direct (short) flow path for the air to be cooled anddivert this air from the shortest flow path into a longer flow path toencourage a turbulence or a turbulent flow. These blocking elements canbe designed as curved elements, which are especially adjustable (claim13, 14). These are oriented in the inlet area and in the outlet area,preferably opposite one another.

With as few right-angled diversions as possible, the invention ensurescountercurrent flow and utilizes the available chambers as completelyand uniformly as possible. Technical experiments were conducted to testthe premise that a heat exchanger achieved more than double the coolingperformance of currently available air heat exchangers in thecountercurrent principle. Values greater than 400 W/°K were achievedwith a heat exchanger with the external dimensions of 100 cm length, 40cm width and 18 cm height (thickness).

The invention is described in detail in the following on the basis ofexemplary embodiments.

FIG. 1 is a view of the flat side 51 of a heat exchanger with an inflowopening 13 and outflow opening 23 to the air to be cooled and/or thecooled air. Two traverses A and B are indicated.

FIG. 2 is a cross-section along plane A of FIG. 1.

FIG. 3 is a cross-section along plane B of FIG. 1.

FIG. 4 illustrates an advantageous augmentation of the arrangement ofFIG. 1, the cross-sections of FIGS. 2 and 3 also applyingcorrespondingly to this arrangement, with the corresponding segments 18,29, which are not drawn into FIGS. 2 and 3.

FIG. 1 illustrates a top view of the flat side 51 of the flatrefrigerating unit. Provided in the flat side 51 are two recesses 13 and23, which are oriented primarily along a central plane A, but aresignificantly spaced from one another in longitudinal direction I of theflat refrigerating unit. They are also arranged at a distance I₂₃, I₁₃between their respective centers and the upper and lower front end ofthe flat refrigerating unit in the front flat side 51. Grooves 23 and 13are circular and, in the cross-section along plane A, cylindrical spacesextent at depth h of the refrigerating unit (see FIG. 2). The width ofthe refrigerating unit extends perpendicular to the length and isreferred to with b in FIG. 1. The refrigerating body is significantlylonger than it is wide. The depth (thickness) in direction h is, inturn, significantly less than the width. However, the depth can also besignificantly increased if a plurality of the sheet metal walls 50 a, 50b, 50 c to be described later are used to define the flow chambers k1,k2, k3, etc.

Assuming a circular opening 13 for entry of the air to be cooled and acircular opening 23 for discharge of the cooled warm air and/or the coldair returning into the circuit cabinet, the storage space 11 behind theinlet 13 and the collection space 21 behind the outlet 23 are bothcylindrical. These areas are also referred to as inlet area and outletarea. Arranged in front of the inlet area 13 is a first axial fan 10,which forces the warm air SL (suction air) to be cooled into an airflowin the first storage chamber 11. A second fan 20 can be arranged in theoutlet opening 23, in order to draw cooled air from the collectionchamber 21 and return it into the cycle as compressed air DL.

Flat side 51 in FIG. 1 is mounted as a wall or to a wall of a cabinethousing, such as a device cabinet, a server cabinet or a circuitcabinet, with corresponding openings, such as a door, a side wall or therear wall. As a result, the openings 13, 23 have access to the interiorof the cabinet, which can also be closed and are usually closed. As aresult of turnover of the warm air volume in the cabinet through theheat exchanger, which, for its part, as a result of refrigerating air KLin the countercurrent principle, causes cooling of the circulatedcabinet air, said refrigerating air then exits as exhaust air AL at theopposite end.

This flow of the refrigerating air KL, L4, AL occurs along the flowchambers, which will be described later in cross-section.

The airflow for cooling is illustrated schematically by the arrows inFIG. 1. It is supported by two inlet fans 30, 31 shown in the drawing,which are arranged adjacent to one another and are electricallyconnected in parallel. Also arranged adjacent to one another and alsoelectrically connected in parallel are two outlet fans 40, 41, all fansbeing based on the principle of axial airflow, that is, with an axis ofrotation and an internal carrier, on which the radial blades thatcompress and move the air are arranged. Air enters axially and exitsaxially, the end of the inlet fans 30, 31 defining the beginning of theheat exchanger and the beginning of the outlet fans 40, 41 defining theend of the heat exchanger.

Because the openings 13, 23 are arranged at a distance from the lowerend and the upper end, they are at a distance b1, b2 and b3, b4,respectively, from the lateral longitudal sides (narrow sides) of theheat exchanger. As a result, the inflow area 13 and the outflow area 23are placed in the heat exchanger in such a way that—viewed in thedirection of flow of the air to be cooled KL—an exchanger surface isalso found upstream from the outlet area 23 and downstream from theinlet area 13. Exchanger surfaces are also provided next to the outletarea and next to the inlet area, so that it is possible to rinse thecollection chamber and/or storage chamber 21, 11, cylindrically shapedin this case.

The flow widths b1, b2 as well as b3, b4 should, taken together in eachcase, at least fall within the range of the diameter d13 and d23 of theopening 13, 23, but, preferably, can also be designed to be larger. Thenumber of axial fans 30, 31, 40, 41 on the inlet face side and theoutlet face side of the flat refrigerating unit depends on thesedimensions. Several axial fans can be connected in parallel, as canfewer.

The heat exchanger is closed on the longitudinal face sides, which isachieved with a stack of fins 52 that completely seal the individualchambers between the back rear wall 50 and the front wall 51 visible inFIG. 1. Sealing fins 32 a, 32 b, 32 c, etc., are also provided in theupper face area, but they only seal every other chamber to the exterior,just as, in the lower face area near the fans 40, 41, only every otherchamber is sealed to the exterior with fins 42 a, 42 b, 42 c, in short,42. The chambers that are sealed with fins 32 or 42 on the face side arethe same chambers, and/or the fins 32, 42 are located at the same planelevel relative to the flat side 51.

This orientation of the flow chambers is illustrated by the two sectionsalong planes A and B, the section along plane A illustrating the storagechamber and the collection chamber 11, 21, where the sectional view inFIG. 3 along plane B illustrates the entire flow path, which shows thatthe fins 32 and the fins 42, respectively, both seal the same chamber onits face (toward the exterior). These flat flow chambers k1, k3, k5, k7are the same flow chambers (with uneven indices) that accept theupward-flowing warm air to be cooled L3. It originates in the collectionchamber 11, as a result of the fan pressure from the suction air SL tothe airflow L1, and terminates in the collection chamber 21, divertedalong the flow path L5 and drawn in by the axial fan 20 to formcompressed air DL at the outlet of the second axial fan 20.

The flow chambers k2, k4, k6, k8, in contact with the exterior air inFIG. 3, are the flow chambers that accept the cooling exterior air L4and, in the countercurrent principle, conduct it to the airflow L3 inthe other chambers with the uneven k-indices. They are not closed withfins at the face ends, but rather in the areas of inflow 13 and outflow23 for the (heated) air to be cooled. The fins shown here, 22 a, 22 b,22 c (22, in short) and 12 a, 12 b, 12 c (12, in short), tightly sealthe exterior air flow spaces from the interior air. In the top view inFIG. 1, these fins are visible, schematically, around the inlet 13 andaround the outlet 23. Like the fins 32, 42, they provide a physicalseparation between the extended, flat flow chambers, which conduct theexterior air, and those of other parallel flow chambers, which conductthe interior air.

The countercurrent principle is evident in FIGS. 2 and 3. FIG. 1 alsoillustrates the stacking of the individual flat flow chambers and theflat extension of these flat flow chambers, with each flow chamberextending between the face-end longitudinal side 52, the face-end narrowsides 32, 42 and the fins 12 and 22, and around the inlet and outletareas. The flat extension of the chambers is significantly larger, interms of its width and length, than the height h of each of thechambers, the height of chamber k1 being indicated as h1 and the heightof chamber k2 as h2 in FIG. 3. The other heights of the other chambersare analogous.

All chambers have, at the same fin height, practically the same height(thickness), each of the chambers being two-dimensionally delimited byindividual layers of sheet metal 50 a, 50 b, 50 c. The sheet metallayers can also be designed to be uneven perpendicular to theirextension, by means of corrugation or embossing, in order to enlarge theheat exchanger surface area between the chambers. However, they areimpermeable to air flow, in order to physically separate therefrigerating air from the air to be cooled.

In an exemplary embodiment, the chamber heights are less than 10 mm,preferably less than 5 mm. In the example, the fins 12, 42 as well as22, 32 are cemented to sheet metal panels 50 a, 50 b, 50 c to achieve anairtight seal. The stacked fins 52 can also be cemented to the sheetmetal in the edge zone in the face-end longitudinal area, and can alsobe reinforced with a screw connection.

In an embodiment of the heat exchanger, as shown in FIG. 4, a curvedcover plate 18, 28 acts as a supplementary flow-blocking element at thelower end of the outlet opening 23 and at the upper end of the inletopening 13. It can extend entirely into the depth of the storage space11 and into the depth of the collection space 21. Otherwise, the heatexchanger shown in FIG. 4 is designed in plane B in the same manner asdescribed on the basis of FIGS. 1 to 3. A sectional view of the heatexchanger shown in FIG. 4 would correspond to exactly the same sectionalview as shown in FIG. 3, with the same countercurrent principle and thesame chamber height of the flat flow chambers. In FIG. 2, a coveringwould occur in the area of discharge of the air to be cooled L3 from theflow chambers near the lower segments of the fins 22 a, 22 b and belowthe upper fin segments 12 a, 12 b upon entry of the air flow L1 into theflow chambers, although said covering would not extend across the entirewidth of the flat flow chambers. In this case, the flow L1 would firstbe diverted into the lateral areas of segments b1, b2 at the inlet, andwould then be conducted along the flat central segment of the currentexchangers. The resulting additional turbulence enhances the turbulentflow effect, thereby providing stronger heat exchange activity andhigher heat transfer output to the counterflowing cooling air L4.

The matching of the electric outputs of the fans, but also of theirsizes or their real operated rotation speed, should preferably occur insuch a way that fan 10 is operated at higher output than fan 20. Thestorage chamber 11 thereby receives a stronger overpressure than can bereduced by the vacuum of the collection chamber 21. This technicaldesign or this technical operation of the heat exchanger also providefor stronger turbulence and an increase in the turbulence effect in theflat flow chambers. Various methods for changing the output of the lowerfans are possible as alternatives. Various fan types (based oninstallation size) can be used as fans 10 or 20. The same fans can beused, but operated differently, and different fans can be used that areoperated differently but based on the same described condition.

In contrast, the fans 30, 31 and 40, 41 should be essentially equal inpower, that is, achieve the same air throughput.

The cooling effects achieved with the described arrangement could beincreased by 20% to 30% if the diversion surface or guide surface, inthe sense of blocking elements 18, 28, were added to the embodimentshown in FIG. 1, which is already outstanding in terms of heat exchangeperformance. In this connection, the dwell time of the air to be cooledin the elongated flat chambers is achieved in addition to the increasein turbulence. The shortest path, that is, the short circuit for the airSL, L3, DL conducted in a U-shaped flow, is blocked and, despite thefact that the essentially U-shaped flow direction is essentiallypreserved, the lateral segments b3, b4, b1, b2 adjacent to the inflowopening 13 and adjacent to the outflow opening 23 are involved in heatexchange, which also applies to the front segment I₂₃ and the rearsegment I₁₃ of the heat exchanger relative to the flow direction of theexterior refrigerating air KL, AL. Around the inlet opening (outside thesealing fins 12) and/or around the outlet opening 23 (around the fins 22that seal here), the external refrigerating air can exert its coolingaction. During the essentially linear passage through the correspondingflat channels k2, k4, k8, the inflow and outflow areas can be flushed.This flushing can be influenced by adjusting the curved blockingelements 18, 28, which adjustment can be oriented in a circumferentialdirection or in an axial direction by pushing in and removing from thecylindrical collection chamber 11 and/or the cylindrical acceptancechamber 21.

The shape of the chambers 11, 21 is not limited to a cylindrical form.Instead, geometries varying within a closer range, such as ellipses andpolygons, can also be selected. It is advantageous, however, when thechamber extends completely into the depth of the heat exchanger andoccupies the entire height of the flat refrigerating unit.

1. Flat refrigerating unit for use with device, server or circuitcabinets or other essentially closed housing arrays for acceptance ofheat-generating equipment, (a) in which the temperature of heated air(SL)—in a countercurrent (L4; L3; k₁; k₂, etc.) with refrigerating air(KL) flowing in the opposite direction—can be reduced without therefrigerating air coming into contact with the air flow (L1, L3, L5) tobe cooled; characterized in that (a) a refrigerating air flow (KL, L4,AL) is conducted in an essentially straight line through chambers (k₂,k₄, k₆, k₈) of the refrigerating unit, between an outlet of at least onefirst fan (30, 31) on the input side of the refrigerating air flow (KL)and an inlet of at least one second fan (40, 41) on the outlet side (AL)of the refrigerating airflow.
 2. Flat refrigerating unit for use withdevice, server or circuit cabinets or other essentially closed housingarrays for acceptance of heat-generating equipment, in which thetemperature of heated air (SL)—in a countercurrent (L4; L3; k₁; k₂,etc.) with refrigerating air (KL) flowing in the opposite direction—canbe reduced without the refrigerating air coming into contact with theair flow (L1, L3, L5) to be cooled; characterized in that (a) the flowof air to be cooled (SL, L1, L3, L5, DL) is only diverted twice, in anessentially right angle; (aa) from an input flow direction (SL), whichprogresses essentially in a direction of the axis of rotation of a thirdfan (10); (bb) into a plurality of chambers (k1, k3, k5, k7) of therefrigerating unit progressing in parallel; (cc) out of the chambers(k1, k3, k5, k7) progressing in parallel into an outlet flow direction(DL), which extends essentially perpendicular to the parallel chambers;(b) to form a U-shaped flow path of the air flow to be cooled.
 3. Flatrefrigerating unit for use with device, server or circuit cabinets orother essentially closed housing arrays for acceptance ofheat-generating equipment, in which the temperature of heated air(SL)—in a countercurrent (L4; L3; k₁; k₂, etc.) with refrigerating air(KL) flowing in the opposite direction—can be reduced without therefrigerating air coming into contact with the airflow (L1, L3, L5) tobe cooled; characterized in that (a) the airflow to be cooled (SL) canbe supplied to a plurality of parallel first chambers (k1, k3, k7)through an inlet area (13), and the refrigerating air (KL) can besupplied to a plurality of parallel second chambers (k2, k4, k6),wherein the parallel first and the parallel second chambers alternate inthe direction of the height or thickness (h) of the refrigerating unit;(b) the alternating chambers (k1, k2, k3, k4, etc.) also extend (l₁₃) ina segment of the flat refrigerating unit, which is disposed between theinlet area (13) and a closer (first) end (40, 41) of the refrigeratingunit, especially the end of the refrigerating unit at which therefrigerating air (KL) is the exhaust air (AL) that can be discharged asa result of cooling.
 4. Flat refrigerating unit for use with device,server or circuit cabinets or other essentially closed housing arraysfor acceptance of heat-generating equipment, in which the temperature ofheated air (SL)—in a countercurrent (L4; L3; k₁; k₂, etc.) withrefrigerating air (KL) flowing in the opposite direction—can be reducedwithout the refrigerating air coming into contact with the air flow (L1,L3, L5) to be cooled; characterized in that (a) the air flow to becooled (SL) can be supplied to an outlet area (23) consisting of aplurality of parallel first chambers (k1, k3, k7), and the refrigeratingair (KL) can be supplied to a plurality of parallel second chambers (k2,k4, k6), wherein the parallel first and the parallel second chambersalternate in the direction of the height or thickness (h) of therefrigerating unit; (b) the alternating chambers (k1, k2, k3, k4, etc.)also extend (l₁₃) in a segment of the flat refrigerating unit, which isdisposed between the outlet area (23) and a closer (second) end (40, 41)of the refrigerating unit, especially the end at which the refrigeratingair (KL) is meant to flow in.
 5. Flat refrigerating unit for use withdevice, server or circuit cabinets or other essentially closed housingarrays for acceptance of heat-generating equipment, in which thetemperature of heated air (SL)—in a countercurrent (L4; L3; k₁; k₂,etc.) with refrigerating air (KL) flowing in the opposite direction—canbe reduced without the refrigerating air coming into contact with theair flow (L1, L3, L5) to be cooled; characterized in that (a) flatchannels progress in parallel to a flat side (51, 50) of the flatrefrigerating unit, wherein the channels have a length (l) and a width(b) in a respective plan that extends, in each case, in parallel to theflat side, and wherein (b1) a height of the channels (h1, h2)perpendicular to the flat side (51, 52) and/or the respective plane issignificantly less than the width (b) of the channels, in order to formflat channels (k1, k2, k3, etc.); or (b2) the flat channels (k1, k2, k3,etc.) extend to an size that essentially corresponds to an entire flatside (50) of the flat refrigerating unit.
 6. Flat refrigerating unit foruse with device, server or circuit cabinets or other essentially closedhousing arrays for acceptance of heat-generating equipment, in which thetemperature of heated air (SL)—in a countercurrent (L4; L3; k₁; k₂,etc.) with refrigerating air (KL) flowing in the opposite direction—canbe reduced without the refrigerating air coming into contact with theair flow (L1, L3, L5) to be cooled; characterized in that (a) sealingseparating elements (12 a, 12 b, 12 c; 22 a, 22 b, 22 c) for the air tobe cooled are provided in an inflow area (13, 11) and/or in an outflowarea (23, 21), with which first channels (k1, k3, k5) for the air to becooled (L3) are separated from second channels (k2, k4, k6) for therefrigerating air (L4); (b) the separating elements (12 a, 22 a, etc.)that seal the inflow area (11) or outflow area (21) of the air to becooled (L3) against the refrigerating air (L4) can be completely flushedby the air flow of the refrigerating air and the air to be cooled. 7.Refrigerating unit according to at least two of the preceding claims 1to
 6. 8. Refrigerating unit according to one of the preceding claims,wherein the fans (30, 31; 40, 41, 10) are executed as axial fans. 9.Refrigerating unit according to one of the preceding claims, wherein the(flat) chambers (k1, k2, k3, k4) are separated from one another by sheetmetal panels (50 a, 50 b, 50 c, etc.) and the heights (h1, h2, etc.) ofthe chambers are formed by a distance between the panels. 10.Refrigerating unit according to one of the preceding claims, wherein, atthe inlet area and the outlet area (13, 23) of both the refrigeratingair and the air to be cooled, fin elements (12, 42, 22, 32) are providedbetween the sheet metal panels (50 a, 50 b) two-dimensionally delimitingthe chambers and/or to close the chambers that are not open at therespective location.
 11. Refrigerating unit according to claim 9 or 10,wherein the sheet metal panels are not smooth, and are, especially,corrugated or embossed.
 12. Refrigerating unit according to one of thepreceding claims, wherein blocking elements (28, 18) are provided in theinlet area for the air to be cooled (SL) and/or in the outlet area forthe cooled air (DL), in order to block direct flow between the inletarea and the outlet area and extend the path of the air to be cooled inthe chambers.
 13. Refrigerating unit according to claim 12, wherein theblocking elements (18, 28) are adjustable.
 14. Refrigerating unitaccording to claim 12 or 13, wherein the blocking elements are curved.15. Refrigerating unit according to one of the preceding claims, whereinthe inlet area (13, 11) and/or the outlet area (23, 21) are designed tobe essentially round and/or, in a height extension (h) of therefrigerating unit, to be essentially cylindrical.
 16. Refrigeratingunit according to one of the preceding claims, wherein the third fan(10) at the inlet area (13, 11) for the air to be cooled (SL) can beoperated at a rotation speed which is greater than a rotation speed of afourth fan (20) at the outlet area for the cooled air (DL, 23),especially at more than 10% greater than the output of the fourth fan(20).
 17. Refrigerating unit according to one of the preceding claims 1to 15, wherein a fourth fan is disposed at the outlet area (21, 23) forthe cooled air, said fourth fan being weaker than the third fan (10).18. Refrigerating unit according to claim 9, wherein the distancebetween the sheet metal panels is determined by fins (12 a, 42 a, 22 a,32 a), and the height (h1, h2) of each respective chamber corresponds tothe fin height.
 19. Refrigerating unit according to the preceding claim,wherein, in order to close each respective chamber, the fins arearranged in such a way that they tightly seal flat chambers for the airto be cooled at the inflow side (30) and outflow side (40) for therefrigerating air and tightly seal the flat chambers for therefrigerating air (KL, L4, AL) at the inflow area and outflow area forthe air to be cooled (11, 21).
 20. Method for cooling air from a device,server or circuit cabinet, or another essentially closed housing arrayfor acceptance of heat-generating equipment, in which the temperature ofheated air (SL)—in a countercurrent (L4; L3; k₁; k₂, etc.) withrefrigerating air (KL) flowing in the opposite direction—can be reducedwithout the refrigerating air coming into contact with the air flow (L1,L3, L5) to be cooled; characterized in that the refrigerating air (KL,AL) flows past an inlet area (13, 11) for the airflow to be cooled (SL,L1) and/or in front of an outlet area (21, 33) for the airflow (L5, DL)already cooled upstream and downstream from the inlet/outlet.
 21. Methodaccording to claim 20, wherein the flow past the inlet area and/or theflow in front of the outlet area occurs at a width (b1+b2; b3+b4) whichis not less than, and is, especially, essentially equal to or greaterthan a width, especially a diameter (d₁₃, d₂₃), of the inflow area (13)or of the outflow area (23).
 22. Method according to claim 20, whereinthe air to be cooled and the refrigerating air (L3, L4) flows intwo-dimensionally extended layers, the height (h1, h2) of which issufficient only to encourage turbulent flow in the layers.
 23. Methodaccording to claim 22, wherein the height of the layers is less than 10mm, or preferably less than 5 mm.
 24. Method according to claim 20,wherein the heated air (SL) supplied with a third fan (10) is suppliedmore intensely, especially at greater output, than that of a fourth fan(20), which extracts the air cooled in the refrigerating unit from therefrigerating unit in the outlet area (23, 21).
 25. Method according toclaim 20, wherein a refrigerating unit according to one of claims 1 to 7is used.